1. Technical Field
The present invention is related to a vibration motor.
2. Description of the Related Art
A vibration motor is a part that converts electrical energy into mechanical vibrations by using the principle of generating electromagnetic forces, and is commonly installed in a mobile phone to generate a soundless vibrating alert. With the rapid expansion of mobile phone markets and increased functionalities added to the mobile phone, mobile phone parts are increasingly required to be smaller and better. As a result, there has been an increased demand for the development of a new structure of vibration motor that can overcome the shortcomings of conventional vibration motors and effectively improve the quality.
As mobile phones having a bigger LCD screen have become popular for the past few years, there have been an increasing number of mobile phones adopting a touch-screen method, by which vibration is generated when the screen is touched. Touch-screens particularly require that the vibration motor has a greater durability due to a greater frequency of generating vibration in response to the touch compared to the vibration bell for incoming calls and that the vibration has a faster response to the touch made on the touch screen, in order to provide a user a greater satisfaction from sensing the vibration when touching the touch screen.
Commonly used to overcome the drawbacks of shorter life time and slower responsiveness in the vibrating functionality of touchscreen phones is a linear vibration motor, does not use the principle of rotating of a motor but uses an electromagnetic force having a predetermined resonant frequency to generate vibrations by use of a spring installed in the vibration motor and a mass coupled to the spring. Here, the electromagnetic force is generated through an interactive reaction between a magnet, which is placed on the moving mass, and a direct or alternating current having a particular frequency flowing through a coil, which is placed on a stationary part.
The spring, which is an essential part of the linear vibration motor, is commonly coupled to the linear vibration motor by way of welding. However, it is difficult to maintain uniform quality of welding. In other words, it is difficult to maintain the quality during the production process because there are many variables, for example, the change in energy, the location and size of welding, and the surface smoothness and adhesion area between the spring and a bracket during the welding, which can cause a change in resonant frequency of the linear vibration motor.